String formatDateTime(DateTime dateTime) {
  // 将 DateTime 对象格式化为 "年-月-日 时:分:秒" 的字符串
  String year = dateTime.year.toString();
  String month = dateTime.month.toString().padLeft(2, '0');
  String day = dateTime.day.toString().padLeft(2, '0');
  String hour = dateTime.hour.toString().padLeft(2, '0');
  String minute = dateTime.minute.toString().padLeft(2, '0');
  String second = dateTime.second.toString().padLeft(2, '0');

  return "$year-$month-$day $hour:$minute:$second";
}